The present invention generally relates to vehicle brake systems, and more particularly relates to a brake force booster with a panic brake function for automotive vehicles.
A brake force booster of this general type is disclosed in the earlier application DE 19750514.7 A1 which is not prior published. In this application, hydraulic provisions are avoided and a brake force booster is disclosed which ensures good controllability of the brake force in the case of normal braking and a high degree of brake force boosting during a panic braking action (quick depression of the brake pedal) along with the possibility of an additional generation (application) of brake force by pedal pressure.
For this purpose, the prior art brake force booster has a clutch device with a sleeve-shaped supporting member interposed between the sliding sleeve and the pressure member. The supporting member, which is supported on a tapered attachment of the valve piston that abuts with its free end on the pressure member, includes on its outside periphery an annular stop with a radial shoulder, at which, in the supporting position of the sliding sleeve, a clutch member makes catch which is pivoted on the sliding sleeve and biassed radially inwards by a spring. In the disengaged position B, i.e., before the relative displacement due to a panic braking B, the said clutch member bears without supporting effect on the circumferential surface of the annular stop.
The object of the present invention is to improve and, in particular, simplify the prior art brake force booster, while maintaining all booster functions.
According to the present invention, this object is achieved in that the supporting member is configured as a component part which transmits the brake force.
With the design according to the present invention, it is no longer necessary to assign a supporting member to the sliding sleeve through which the valve piston must be passed. The valve piston, by abutment on the supporting member, can rather transmit the entire mechanical brake force by way of the supporting member onto the pressure member and the reaction member and, if necessary, can even adopt itself the function of the supporting member. This also obviates the need for the pivotable mounting support of the clutch member and a separate spring for biassing the clutch member, for example, by using a spring arm made of spring steel as a clutch member. The use of a permanent magnet for the temporary support of the sliding sleeve in the brake actuation direction is also advantageous. Coupling engagement is then effected by mutual approach of the two parts being coupled, while the disengagement is simply carried out by a relative displacement between the parts, and with one part being retained mechanically by means of a stop.